DE3501037A1 - Distance measurement in vehicles - Google Patents

Abstract

The invention relates to a method for measuring the distance of vehicles travelling one behind the other. The vehicles measure the distance covered from marks applied to the road and transmit to one another in a wireless fashion the value obtained. The distance between the vehicles is calculated from the values obtained in this way. The said distance can be displayed or used for directly influencing the driving behaviour. <IMAGE>

Description

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Distance measurement in vehicles

The invention relates to a method for measuring distances in vehicles.

Many accidents in traffic with motor vehicles are so-called Rear-end collisions. These arise essentially from the fact that the distance to the required to brake the vehicle vehicle in front is not complied with despite legal regulations. In addition, the driver as a result not reacting or reacting too late to a reduction in distance due to inattentiveness or fatigue.

There is a particular risk of rear-end collisions when the view is obstructed through fog and heavy snowfall, which often lead to pile-ups with high levels of personal injury and property damage.

Timely recognition of a too small distance or its sudden reduction is a prerequisite for a timely and doing the right thing. Since, as practice shows, people are often overwhelmed, it is necessary to im to support ever denser and faster traffic through technical means and to help reduce the risk of accidents to reduce.

One method that is intended to serve this goal is known under the name of distance warning radar. It relies on that The vehicle emits a bundled radar beam in the direction of travel, which is reflected off a fixed obstacle or the vehicle in front. From the term to for the re-arrival of the reflected radar beam, the distance to the reflecting object can be determined. If this method is used primarily to determine the distance to a vehicle in front, then occur through reflections that can hardly be avoided

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Immobile objects near the road, such as guard rails, Falsification of the measurement results, which is easy to can lead to uncertainty for the driver.

The invention, as it is specified in the claims, shows a method which rules out these falsifications.

The starting point for this process is provided by stationary markings on or in the immediate vicinity of the roadway on which there is move the vehicles whose distance is to be measured.

^{Such markings can, for example, represent lines 7 or 7 1} which differ from the rest of the road surface in terms of their absorption, reflection, conductivity or radiation behavior.

A traveling across this marking vehicle B detects this by, for example, 1 ¹ Energy from a source - preferably light energy in the visual range - radiates to the road surface and receives the reflected radiation. The energy received is received by a receiver 2 'and fed to an evaluation device 3'. If the line is implemented by an active transmitter, the transmitter ¹¹ or 1 in the vehicle can be omitted.

This evaluation device 3 ″ is also connected to the measuring device of vehicle B, which determines the distance covered. A ^{counting device contained in evaluation device 3 1} _{records the distance S 2} traveled by vehicle B since it crossed the marking 7 ¹ (in the case of a vehicle A ahead, the Distance S ₁ ).

In vehicle A, 1 is an optical one in the exemplary embodiment Transmitter, with 2 denotes the associated receiver. 3 is the

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Evaluation device. 4 represents a radio transmitter and 5 the associated one Radio receiver.

The transmission by radio can also be by optical transmission and vice versa.

Each vehicle A, B transmits by means of a Senders.4, 4 'preferably by radio 8, 8' continuously or at intervals the instantaneous value of the distance s. To the receiver 5, 5 ^1, preferably to after vehicle B, the latter to its Evaluation device 3 ¹ forwards. The evaluation device 3 'of the vehicle B driving behind now calculates the distance a _Q to the vehicle A ahead _{from the difference s - S 2.}

The measured distance value obtained in this way can opv. table and / or acoustically, depending on the driving speed in an optical and / or acoustic warning implemented and / or converted into control signals to influence the brake and / or fuel supply. Serves for this a display and control device 6 'in the following vehicle B or 6 in vehicle A.

In order to limit the influence of the measuring inaccuracies of the distance measuring devices of the vehicles involved, it makes sense to repeat the stationary marking at certain intervals and thus to initiate _{a new start of the measurements of s and s 2.} The repetition of the marking is not subject to any regulation with regard to certain distances Sg between 7 and 7 ^{1 to be maintained} .

If the preceding vehicle A has already passed the next marking 7, but vehicle B has not yet, the evaluation device 3 ″ of vehicle B adds the value s _{Q to the associated distance value S 1} , not shown, until the new marking is reached. It is

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Sq is the last value of s transmitted to vehicle B before the start of the new measurement and represents the distance between the two markings 7 and 7 ¹

a _Q = S ₁ , + S ₀ - s ₂ .

In the practical application of the method, it is necessary to precisely determine the vehicle distances a ^, the distances a. and _{include a 2} in the calculation. The distances a. and a ₂ are dependent on the installation location of the transmitter devices 1 or ¹¹ and receiver devices 2 or 2 'of the vehicles, which are used to recognize the marking. So there is a. the distance from the measuring point of vehicle A to its rear boundary, a ₂ the measuring point distance to the front boundary of vehicle B.

Since the values of a. and a ₂ depend on the respective vehicle, they must be taken into account by the evaluation device 3 or 3 ^{1 of} the respective vehicle. Thus, in practice, vehicle A sends the value S ₃ = S ₁ -a ₁ to receiver 5 ¹ of vehicle B instead of value s

^a 3 ^{= S} 3 " ^S 2" ^a 2 *

The measurement inaccuracies in the measurement of the distances S ₁ and S ₂ arise essentially from changes in the rolling circumference of the vehicle wheels, for example as a result of tire wear or the fitting of different types of tires.

By arranging two stationary markings at a fixed distance s _Q (eg 1 km), the distance measuring device of the vehicles can be calibrated. Such calibration routes can be added to the driving routes at any frequency

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can be inserted, even if the stationary markings are otherwise attached at irregular intervals. A distinction as to whether it is a normal mark at the start of the distance measurement from S ₁ or S ₂ or whether the function as a calibration route is also fulfilled can be made, for example, by special design of the markings at the beginning and at the end of the calibration route (e.g. by Doubling of the normal marking or any other coding, such as changing the distance, the width, the absorption, reflection or radiation behavior).

If several vehicles A, B driving one behind the other are equipped with the method according to the invention for distance measurement and the result of this measurement is used depending on the driving speed v _A , Vg to automatically influence the speed by controlling the fuel supply and the braking device, then even in normal driving operation - therefore advantages for the vehicle driver not only in critical situations.

In order to keep the speed of a vehicle constant over long distances at a predetermined value and thereby the To relieve the driver of the necessary correction processes are appropriate automatic control devices, e.g. known as cruise control. Special spread have experienced such facilities in the USA, where the speed is limited to a maximum of 60 miles and on Long distances are covered on the highways with relatively little traffic. In the Federal Republic of Germany, however driven at very different speeds on the motorways due to the lack of limitation. Also is here the traffic density is considerably higher. As a result, the desired speed is rarely achieved over long periods of time Stretch can be maintained constant. With that one loses

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automatic speed control of the type mentioned considerably in use value. If you now connect the device for compliance a desired speed with the inventive Method of distance measurement, it is achieved that the vehicle is automatic

° whenever possible, drive at the desired speed,

° the safety distance from the vehicle in front, which changes with the speed adheres to.

In other words: several vehicles driving one behind the other behave like the pearls of a chain, whereby the chain cord is made of rubber and move with increasing speed stretches. The knots between the pearls prevent the pearls from touching each other (minimum distance between vehicles) .

Instead of the described transmission of the values s. Or Sg from vehicle A to vehicle B, which indicate the distance of vehicle A from the stationary marking last passed, the transmission of the point in time t «of the crossing over the marking and then the continuous transmission can also be carried out the current speed v. of vehicle A. From this information, the evaluation device 3 ′ of vehicle B is able to determine the corresponding value of s itself ^{with the aid of the time t that has passed since vehicle A has passed over the marking 7 1.}

The inventive method allows depending on the transmission direction between the vehicles the determination of the distance to both the preceding and the following Vehicle.

This continuous transmission of information about the current vehicle speed can be used, for example, for the following purposes can also be used:

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Monitoring of compliance with the speed limit by the police by means of a simple recipient. This can replace the conspicuous and time-consuming radar controls.

Detection of the number and the speed of those approaching an intersection, for example Vehicles and, derived from this, control of traffic control devices (e.g. traffic lights).

Another advantage of the method according to the invention is that due to the low equipment-related expense and the mode of action its use in two-wheeled vehicles is possible.

Claims (8)

ANT Nachrichtenentechnik GmbH E7 / Sch / ht Gerberstraße 33 BK 84/117 D-7150 Backnang Patent claims: 1. A method for measuring the distance between vehicles driving one behind the other A, characterized in that, starting from a corresponding marking on, in or in the immediate vicinity of the lane, the vehicles passing this marking determine their respective distance from this marking, this value being the same as the distance measurement involved vehicle transmit that this vehicle calculates the distance between these two vehicles from the difference between its own distance to the marking and the corresponding distance cres that vehicle from which the distance value was transmitted. 2. The method according to claim 1, characterized in that the markings are arranged at least on one roadway. 3. The method according to any one of the preceding claims, characterized in that the markings are attached at regular intervals in the direction of travel. - 2 - BK 84/117 4. The method according to any one of the preceding claims, characterized in that the markings are coded, preferably for calibrating the distance measuring device in the vehicles in order to compensate for measurement errors caused by different rolling circumference of the wheels. 5. The method according to any one of the preceding claims, characterized in that the markings are realized by active radiators. 6. The method according to any one of the preceding claims 1 to 4, characterized in that the markings are implemented passively by reflection, absorption or conductivity properties that differ from their surroundings. 7. The method according to any one of the preceding claims, characterized in that a device for recognizing the marking in the form of a transmitter and / or receiver is provided in the vehicle, that a transmitter is present for transmitting the values from which the distance covered by the transmitting vehicle since the marking has been passed, as well as a receiver in the other vehicle involved in the measurement to record the sent values and that an evaluation device is available to calculate the difference between the distances between the vehicles involved in the measurement and the marking and that a display and / or control device is provided which displays the determined distance between the vehicles to the driver and / or has a regulating effect on the driving behavior of the vehicle. 8. The method according to any one of the preceding claims, characterized in that the vehicle-related values with respect to the length of the vehicle and the installation location of the device used to recognize the marking on the vehicle by the evaluation device in the respective ■■■■ IB - 3 - BK 84/117 Vehicle are taken into account in order to determine the actual distance between the vehicles. Method according to one of the preceding claims, characterized in that a programmable weighing distance is maintained to the preceding vehicle according to the vehicle speed by appropriate regulation of the driving data.